Many believe a Euro sceptic influx will further undermine the legitimacy of the European Union.

Marine Le Pen and Geert Wilders promise to slay "the monster in Brussels"

If, as many polls predict, the Euro sceptics emerge as the third largest bloc in the Brussels Parliament after the elections, the ECFR report says "we may see the strange spectacle of a parliament with many members who ultimately want to secure its own abolition".

Marine Le Pen, the leader of France's Front National, and Geert Wilders, the anti-Islam campaigner and leader of the Dutch Party of Freedom, have agreed to build a pan-European parliamentary group to wreck the European parliament from within, and, as they put it, slay "the monster in Brussels".

This voting bloc could mean a large portion of the assembly becomes dedicated to paralysing the progress of its own legislation and polarising debates in the parliament.

Le Pen and Wilders Unite

Eurosceptic Dutch politician Geert Wilders and French National Front (FN) leader Marine Le Pen launched what they call an "historic" alliance last November.

The two have united over their belief in the need to repatriate from Brussels the power to control their countries' borders and economies.

Both leaders say Europe's political elite has been too tolerant of Islam and both want to curb immigration.

At the launch of the group Ms Le Pen declared "the time of patriotic movements being divided is over".

"Today is the start of the liberation of Europe from the monster of Brussels," said Mr Wilders, who heads the Freedom Party.

William Dartmouth, the UKIP MEP for the South West of England and Gibraltar, does not see it that way.

"It seems to be a very odd mindset to say that a mockery is made if there is a proper argument made and proper scrutiny - which there certainly isn't at the moment," he says.

Back door

The Euro sceptic surge could, ironically, lead to a stronger pro-EU bloc, with a common enemy to unite against.

The traditional pro-European, mainstream parties have dominated the European Parliament through the two largest voting blocs - the centre right European People's Party (EPP) and centre-left Progressive Alliance of Socialists and Democrats (S&D).

These two groups are expected to have about 200 seats each after May's elections - out of a total of 751 MEPs.

If the polls are correct, they will be confronted by a Euro sceptic bloc of a similar size, which could block and frustrate legislation.

If the three largest groups, S&D, the EPP and the Alliance of Liberals and Democrats for Europe (ALDE) were to group together they'd have close to 500 votes, giving them a comfortable two-thirds majority to pass key legislation on the single market, trade, and euro zone governance issues.

Will Eurosceptics will be able to stick together once in the European Parliament?

"The incentive is for these main groups to compromise so that by themselves they can win the majority of the European Parliament without depending on the smaller groups, which are more Eurosceptic," says Yves Bertoncini, Director of the pro-EU Think Tank the Jacques Delors Institute.

MEPs might also turn to passing legislation through the back door - using emergency powers and intergovernmental treaties rather than through the parliament.

Yet the European Council on Foreign Relations warns that huddling too close together could strengthen claims that there is a remote European cartel, alien to the concerns of voters, ganging up on the Eurosceptics.

Fascistic parties

European Elections 2014

The eighth European elections since direct voting began in 1979 will take place from 22-25 May

An electorate of over 400m from 28 countries will choose 751 representatives (down from 766 at the last elections) to represent them in the European Parliament

Each member state has its own electoral laws and each decides on what day its citizens will go to the polls

Seats are allocated among the various states on the basis of 'degressive proportionality', meaning countries with larger populations have more seats than smaller ones but the smaller states have more seats than strict proportionality would imply

British voters will turn out on 22 May to elect their 73 MEPs.

Turnout has steadily declined from 63 percent in 1979 to just 43 percent in 2009

The ability of the Eurosceptic parties to work together is also under question.

Left leaning Eurosceptic groups such as the Left Front in France and Syriza in Greece are unlikely to collaborate with their right wing counterparts.

Le Pen and Wilders have ruled out collaborating with what they see as overtly fascistic parties such as Golden Dawn in Greece and Jobbik in Hungary.

But UKIP leader Nigel Farage has ruled out an alliance with the far right Front National - unlike Italy's Northern League, who are expected to leave the UKIP led Europe of Freedom and Democracy (EFD) to join the planned new voting bloc.

If the Northern League do go the EFD risks collapse, as groups need at least 25 MEPs from seven countries to be given official status. The EFD currently have 31 MEPs.

The European Parliament will then, according to Mr Bertoncini, continue to work largely based on the compromises built by the dominant political groups.

"There will be a populist upswing in the next European election, but the thing is the populists are not a family. So of course they will be weaker because they are not united," says Mr Bertoncini.

Biggest impact

"The common point for these parties is they don't like Europe, but the roots of the criticism from the left and the right are different. They are different in terms of solutions as well."

He added: "There will be more vocal protestors in the European Parliament after May but they won't be decision makers, because they are in the minority. In terms of concrete decision making they are useless."

But Jose Ignacio Torreblanca, one of the authors of the European Council on Foreign Relations report, does not think the Eurosceptics need a majority in the European Parliament to impose their agenda.

The biggest impact of the surge will come from Eurosceptics' ability to "condition other mainstream parties, to moderate them or make them change their agenda", he argues.

And with an aversion to increasing European integration already shared by some the bigger and more established parties they might find themselves pushing at an open door.